Conventionally, an internal combustion engine includes an engine driving pump, and is configured to circulate lubricant to each part of the internal combustion engine by driving the pump.
Further, for example, Patent Document 1 describes a configuration in which a supply passage of lubricant is provided with a pressure relief valve that is able to change a relief pressure, and when demand for the lubricant is small, the relief pressure of the pressure relief valve is decreased so as to execute a low-pressure control to limit a circulation amount of the lubricant. According to such a configuration, it is possible to reduce that driving load of the pump which acts on the internal combustion engine by executing the low-pressure control, thereby eventually restraining fuel consumption of the internal combustion engine.
In the meantime, at the time of starting the internal combustion engine, such a situation occurs that the lubricant in the supply passage flows out during stop of the engine before the starting and the lubricant is not left in the supply passage. In view of this, such a technique has been proposed that at the time of starting the internal combustion engine, the execution of the low-pressure control is prohibited, so that a pressure of the lubricant in the supply passage is brought to a high state right after the engine starting, thereby allowing the lubricant to go around to ends of the supply passage immediately.
Further, conventionally, such a technique has been known that, when a predetermined automatic stop condition, such as a condition in which a vehicle speed is a predetermined speed or less and an accelerator pedal is not stepped on, is established during an engine operation, a control to stop the engine operation automatically, that is, a so-called idle reduction control is executed so as to restrain fuel consumption of the internal combustion engine. Note that, during the automatic stop, when a predetermined restart condition, such a condition in which the accelerator pedal is stepped on again, is established, the internal combustion engine is restarted.